Question

29 Nervous system develops m ) Mesoderm 9 Trophoblast so in which of the following types does animal embrys develp within the uterus and is A) nourished by yotk sac? C) Viviparous D) None of the above. E) All of the above 31. What is characteristic of ecdysozoans? Al A deuteristome condition B) )Some kind of exoskeleton, or hard outer covering Agile, speedy, and powerful locomotion D) A pseudocoelom E) The diploblastic condition 32 Which of the following is NOT characteristic of birds? A) Hollow bones B) Amnion ) High metabolic rate D) Ectothermy E) reptilian-like scales on legs Fertilization in the earthworm is accomplished by the use of the nephridia flame cells 33. Bclitellium D. trachea E. typhosole

Answer 1

1) The answer is option D.

The mammalian central nervous system (CNS) is derived from the ectoderm—which is the outermost tissue layer of the embryo. During gastrulation cells migrate to the interior of the embryo, forming three germ layers— the endoderm (the deepest layer), mesoderm and ectoderm (the surface layer)—from which all tissues and organs will arise and the ectoderm gives rise to skin and nervous system,

2) The answer is option A

It is a mode of reproduction in animals in which embryos that develop inside eggs remain in the mother's body until they are ready to hatch. But the embryos have no placental connection with the mother and receive their nourishment from a yolk sac.

3) The answer is option B

The main characteristic feature of ecdysozoans is they shed their protective cuticle or exoskeleton during their growth. This process is called as ecdysis or molting

4) The answer is option D

Birds are endothermic because when they fly, they require large amounts of energy, for high metabolic rate. when compared to mammals, which are also endothermic, birds have an insulating covering that keeps heat in the body: feathers. Specialized feathers called down feathers are especially insulating, trapping air in spaces between each feather to decrease the rate of heat loss. Certain parts of a bird’s body are covered in down feathers; the base of other feathers have a downy portion, while newly-hatched birds are covered in down.

5)The answer is option B

  To copulate, two worms line up against each other facing opposite directions. In this position, both worms excrete so much mucous, that what is called a slime tube forms around their bodies. Each worm ejaculates sperm from its sex organs into this slime tube and it is then deposited in the other worm's sperm receptacle. The act of mating is completed, but the process of reproduction still continues as each worm goes its separate way. There is a wide band near the front of any earthworm. That band is called the clitellum and it's responsible for producing another tube of mucus. This band is passed forward toward the mouth end of the worm. As it travels forward, the mucus passes over the sacs containing the worm's own eggs, and it sticks to the slime. Attached to the slime tube, the eggs then pass over the seminal receptacle, where the other worm's sperm is kept. The eggs and sperm come in contact in the slime tube, the eggs are then fertilized.